There are conventionally known electrical connection boxes that include a casing that houses a circuit portion on which electronic components are mounted. JP 2014-82844A discloses an electrical connection box that includes: a circuit portion on which electronic components are mounted; an electrically-conductive heat dissipation member that dissipates heat from the circuit portion; and an electrically-conductive casing in which the circuit portion is housed so as to be located between the casing and the heat dissipation member.
In the case where an electrical connection box and electricity storage devices are mounted on a vehicle or the like, if they are separately mounted, the space for mounting them increases, and electrical wires and connectors for connecting them are needed. Therefore, there is a problem in that the number of components increases, the weight increases, and electrical power transmission loss occurs due to the resistance of the electrical wires.
On the other hand, it is preferable that the circuit portion and the electricity storage devices of the electrical connection box are mounted together because the space for mounting them can be reduced, an increase in the weight due to the presence of electrical wires, connectors, and so on can be suppressed, and electrical power transmission loss due to the resistance of the electrical wires is prevented from occurring.
JP 2005-94943A discloses a capacitor unit that includes: a capacitor block; a control circuit portion that is constituted by a charging/discharging circuit for charging or discharging the capacitor block; and a casing in which the capacitor block and the control circuit portion are housed. The casing is constituted by a lower casing and an upper cover. The capacitor block is housed in the lower casing and is fixed using screws.
However, if the circuit portion and the electricity storage devices are mounted together, there is a concern that a problem will occur due to the weight of the electricity storage devices because electricity storage devices are usually heavy. According to JP 2005-94943A, the capacitor block is fixed to the casing. However, this casing has a configuration for not only covering the entire body of the capacitor block and the control circuit portion, but also fixing the capacitor block and the heat dissipation plate of the control circuit portion. Therefore, there is a problem in that the configuration of the casing is complex, and it is not easy to miniaturize the configuration of the capacitor unit.
The present invention has been completed based on the above-described situation, and aims to form an electricity storage unit that can prevent the circuit portion from being damaged, without increasing the size of the electricity storage unit despite the circuit portion and the electricity storage devices being mounted together.